1. Chapter 1 Ten Principles of Economics
N. Gregory Mankiw
Seventh Edition
Lou, Fang School of Economics, Shanghai University of Finance and

2. In this chapter, look for the answers to these questions
What kinds of questions does economics address?
What are the principles of how people make decisions?
What are the principles of how people interact?
What are the principles of how the economy as a whole works?
Lou, Fang School of Economics, Shanghai University of Finance and

3. What Economics Is All About
Scarcity: the limited nature of society’s resources
Economics: the study of how society manages its scarce resources, e.g.
how people decide what to buy, how much to work, save, and spend
how firms decide how much to produce, how many workers to hire
how society decides how to divide its resources between national defense, consumer goods, protecting the environment, and other needs
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4. The principles of HOW PEOPLE MAKE DECISIONS
Decision-making is at the heart of economics. The individual must decide how much to save for retirement, how much to spend on different goods and services, how many hours a week to work. The firm must decide how much to produce, what kind of labor to hire. Society as a whole must decide how much to spend on national defense (“guns”) versus how much to spend on consumer goods (“butter”).
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5. PRINCIPLE 1 People Face Tradeoffs
All decisions involve tradeoffs. Examples:
Going to a party the night before your midterm leaves less time for studying.
Having more money to buy stuff requires working longer hours, which leaves less time for leisure.
Protecting the environment requires resources that could otherwise be used to produce consumer goods.
Lou, Fang School of Economics, Shanghai University of Finance and

6. PRINCIPLE 1 People Face Tradeoffs
Society faces an important tradeoff: efficiency vs. equality
Efficiency: when society gets the most from its scarce resources
Equality: when prosperity is distributed uniformly among society’s members
Tradeoff: To achieve greater equality, could redistribute income from wealthy to poor. But this reduces incentive to work and produce, shrinks the size of the economic “pie.”
Lou, Fang School of Economics, Shanghai University of Finance and

7. PRINCIPLE 2 :The Cost of Something Is What You Give Up to Get It
Making decisions requires comparing the costs and benefits of alternative choices.
The opportunity cost of any item is whatever must be given up to obtain it.
It is the relevant cost for decision making.
Lou, Fang School of Economics, Shanghai University of Finance and

8. PRINCIPLE 2 :The Cost of Something Is What You Give Up to Get It
Examples: The opportunity cost of…
…going to college for a year is not just the tuition, books, and fees, but also the foregone wages.
…seeing a movie is not just the price of the ticket, but the value of the time you spend in the theater.
Lou, Fang School of Economics, Shanghai University of Finance and

9. PRINCIPLE 3 Rational People Think at the Margin
systematically and purposefully do the best they can to achieve their objectives.
make decisions by evaluating costs and benefits of marginal changes, incremental adjustments to an existing plan.
Lou, Fang School of Economics, Shanghai University of Finance and

10. PRINCIPLE 3 Rational People Think at the Margin
Examples:
When a student considers whether to go to college for an additional year, he compares the fees & foregone wages to the extra income he could earn with the extra year of education.
When a manager considers whether to increase output, she compares the cost of the needed labor and materials to the extra revenue.
Lou, Fang School of Economics, Shanghai University of Finance and

11. PRINCIPLE 4 People Respond to Incentives
Incentive: something that induces a person to act, i.e. the prospect of a reward or punishment.
Rational people respond to incentives.
Examples:
When gas prices rise, consumers buy more hybrid cars and fewer gas guzzling SUVs.
When cigarette taxes increase, teen smoking falls
Lou, Fang School of Economics, Shanghai University of Finance and

12. ACTIVE LEARNING 1 Applying the principles
You are selling your 1996 Mustang. You have already spent $1000 on repairs.
At the last minute, the transmission dies. You can pay $600 to have it repaired, or sell the car “as is.”
In each of the following scenarios, should you have the transmission repaired? Explain.
A. Blue book value (what you could get for the car) is $6500 if transmission works, $5700 if it doesn’t
B. Blue book value is $6000 if transmission works, $5500 if it doesn’t
Most of these PowerPoint chapters have two or three Active Learning activities. They break up the lecture with short in-class activities for immediate reinforcement, application, or assessment of the material in the preceding slides. A good idea is to give students time to formulate their answers before asking for volunteers to share their answers with the class. When the questions or exercises are more complex, consider having them work in pairs.
Digression on class participation:
In general, it’s not a good idea to try to solicit participation by saying “Who can tell me the answer to X?” The invariable result is regular participation by very few students —the quick thinkers who have the confidence to answer spontaneously in front of the class—with little participation from anyone else. Better is to give students a quiet moment to think through their answers before requesting volunteers.
Better yet is a simple, time-tested activity called “THINK-PAIR-SHARE.” Pair students up. Pose a question or problem. Have students work on the problem individually for a couple minutes. Then, allow a couple minutes for pair work: each student tries to explain to the other why his or her answer is correct, and the other offers feedback. In many cases, students come up with better answers by working together. After this pair time, ask for volunteers. Students are much more likely to participate since they’ll have had the opportunity to test run answers by a classmate. And those who do not participate will at least have had the chance to share their answer with, and get feedback from, one other student.
Activities like these are useful to break up a lecture every 20 minutes or so. They help maintain students’ attention spans and increase their comprehension of the material you cover. These activities are also useful for quick, informal assessment – often, they will alert you to problems in student understanding, which you can then correct before moving on to cover additional material.
End of digression.
Lou, Fang School of Economics, Shanghai University of Finance and

13. ACTIVE LEARNING 1 Answers
Cost of fixing transmission = $600
A. Blue book value is $6500 if transmission works, $5700 if it doesn’t
Benefit of fixing transmission = $800 ($6500 – 5700).
Get the transmission fixed.
B. Blue book value is $6000 if transmission works, $5500 if it doesn’t
Benefit of fixing the transmission is only $500.
Do not pay $600 to fix it.
Lou, Fang School of Economics, Shanghai University of Finance and

14. ACTIVE LEARNING 1 Observations
The $1000 you previously spent on repairs is irrelevant. What matters is the cost and benefit of the marginal repair (the transmission).
The change in incentives from scenario A to scenario B caused your decision to change.
If you wish, omit this slide and just give this information to the class verbally.
Lou, Fang School of Economics, Shanghai University of Finance and

15. The principles of HOW PEOPLE INTERACT
Whether we’re talking about the U.S. economy or the local economy, the term “economy” simply means a group of people interacting with each other.
These interactions play a critical role in the allocation of society’s scarce resources. For example, the interaction of buyers and sellers determines the prices of goods and the amounts produced and sold. These interactions are an important part of what economists study.
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16. PRINCIPLE 5 Trade Can Make Everyone Better Off
Rather than being self-sufficient, people can specialize in producing one good or service and exchange it for other goods.
Countries also benefit from trade and specialization:
Get a better price abroad for goods they produce
Buy other goods more cheaply from abroad than could be produced at home
Lou, Fang School of Economics, Shanghai University of Finance and

17. PRINCIPLE 6: Markets Are Usually A Good Way to Organize Economic Activity
Market: a group of buyers and sellers (need not be in a single location)
“Organize economic activity” means determining
what goods to produce
how to produce them
how much of each to produce
by what price to sell them
who gets them
Lou, Fang School of Economics, Shanghai University of Finance and

18. PRINCIPLE 6: Markets Are Usually A Good Way to Organize Economic Activity
A market economy allocates resources through the decentralized decisions of many households and firms as they interact in markets.
Famous insight by Adam Smith in The Wealth of Nations (1776):
Each of these households and firms acts as if “led by an invisible hand” to promote general economic well-being.
Lou, Fang School of Economics, Shanghai University of Finance and

19. PRINCIPLE 6: Markets Are Usually A Good Way to Organize Economic Activity
The invisible hand works through the price system:
The interaction of buyers and sellers determines prices.
Each price reflects the good’s value to buyers and the cost of producing the good.
Prices guide self-interested households and firms to make decisions that, in many cases, maximize society’s economic well-being.
Lou, Fang School of Economics, Shanghai University of Finance and

20. PRINCIPLE 7 : Governments Can Sometimes Improve Market Outcomes
Important role for govt: enforce property rights (with police, courts)
People are less inclined to work, produce, invest, or purchase if large risk of their property being stolen.
Lou, Fang School of Economics, Shanghai University of Finance and

21. PRINCIPLE 7 : Governments Can Sometimes Improve Market Outcomes
Market failure: when the market fails to allocate society’s resources efficiently
Causes of market failure:
Externalities, when the production or consumption of a good affects bystanders (e.g. pollution)
Market power, a single buyer or seller has substantial influence on market price (e.g. monopoly)
Public policy may promote efficiency.
Lou, Fang School of Economics, Shanghai University of Finance and

22. PRINCIPLE 7 : Governments Can Sometimes Improve Market Outcomes
Govt may alter market outcome to promote equity.
If the market’s distribution of economic well-being is not desirable, tax or welfare policies can change how the economic “pie” is divided.
Lou, Fang School of Economics, Shanghai University of Finance and

23. ACTIVE LEARNING 2 Discussion Question
In each of the following situations, what is the government’s role? Does the government’s intervention improve the outcome?
a. Public schools for K-12
b. Workplace safety regulations
c. Public highways
d. Patent laws, which allow drug companies to charge high prices for life-saving drugs
The items in this list are meant to get students thinking about Principles 6 and 7 in the context of specific examples, and to generate discussion rather than arrive at definitive answers.
NOTE: Discussing the entire list would consume a lot of class time (20-25 minutes). Two would suffice. Pick your favorite two and delete the others. Of course, you can skip this slide entirely if you wish to get through the chapter as quickly as possible. Here are some notes that might help guide the discussion:
a. Public schools. The alternative would be private schools. The cost of education would be concentrated among those with school-aged children, rather than spread over all taxpayers, so the price per child would likely be high. Some families would not be able to afford to enroll their children in schools, and would either home-school the children or raise them without education. Is the benefit to society of having an educated population large enough to justify making people without children share in the cost? Could the private sector provide education more efficiently (either at lower cost or higher quality) than the public sector?
b. Workplace safety regulations. Without such regulations, would firms provide a safe environment for their workers? Some students will say “no—look at how bad working conditions are in poor countries that have no safety regulations.” Another view is that dropping such regulations would make workers better off. Workers may view the safety of their work environment as part of their wage: the less safe the environment at a specific firm, the higher the wage the firm will have to offer to make workers willing to work there. If workers vary with respect to their tolerance for unsafe conditions, then workers with a high risk tolerance would be better off if given the option to work for higher wages in factories that aren’t as safe. Such workers would be worse off if the government required all firms to provide equally safe conditions.
c. Public highways. The alternative would be toll highways operated by the private sector. People who use highways more would pay more, and people who use them less would pay less, which seems fairer than having everyone pay equally for highways. (Actually, everyone does not pay equally - people who use public roads more buy more gas, and therefore pay more gas tax.) If there are external benefits to society of having a national highway system, then the private sector would under-provide this good.
d. Patent laws. I’ve kind of loaded the question with the wording on the slide. If you wish, change it to just “Patent laws.” Is it fair that drug companies charge such high prices for drugs that some people need to stay alive? If drug prices are regulated, how might pharmaceutical firms respond?
Lou, Fang School of Economics, Shanghai University of Finance and

24. The principles of HOW THE ECONOMY AS A WHOLE WORKS
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25. Huge variation in living standards across countries and over time:
PRINCIPLE 8: A Country’s Standard of Living Depends on Its Ability to Produce Goods & services
Huge variation in living standards across countries and over time:
Average income in rich countries is more than ten times average income in poor countries.
The U.S. standard of living today is about eight times larger than 100 years ago.
Lou, Fang School of Economics, Shanghai University of Finance and

26. PRINCIPLE 8: A Country’s Standard of Living Depends on Its Ability to Produce Goods & services
The most important determinant of living standards: productivity, the amount of goods and services produced per unit of labor.
Productivity depends on the equipment, skills, and technology available to workers.
Other factors (e.g., labor unions, competition from abroad) have far less impact on living standards.
Lou, Fang School of Economics, Shanghai University of Finance and

27. PRINCIPLE 9: Prices Rise When the Government Prints Too Much Money
Inflation: increases in the general level of prices.
In the long run, inflation is almost always caused by excessive growth in the quantity of money, which causes the value of money to fall.
The faster the govt creates money, the greater the inflation rate.
Lou, Fang School of Economics, Shanghai University of Finance and

28. PRINCIPLE 10: Society Faces a Short-run Tradeoff Between Inflation and Unemployment
In the short-run (1–2 years), many economic policies push inflation and unemployment in opposite directions.
Other factors can make this tradeoff more or less favorable, but the tradeoff is always present.
Lou, Fang School of Economics, Shanghai University of Finance and

29. Summary The principles of decision making are: People face tradeoffs.
The cost of any action is measured in terms of foregone opportunities.
Rational people make decisions by comparing marginal costs and marginal benefits.
People respond to incentives.
Lou, Fang School of Economics, Shanghai University of Finance and

30. Summary The principles of interactions among people are:
Trade can be mutually beneficial.
Markets are usually a good way of coordinating trade.
Govt can potentially improve market outcomes if there is a market failure or if the market outcome is inequitable.
Lou, Fang School of Economics, Shanghai University of Finance and

31. Summary The principles of the economy as a whole are:
Productivity is the ultimate source of living standards.
Money growth is the ultimate source of inflation.
Society faces a short-run tradeoff between inflation and unemployment.
Lou, Fang School of Economics, Shanghai University of Finance and